US President Donald Trump believes his tariffs on India for purchasing Russian oil was a "big blow" to Moscow's economy as a 50 per cent duty has been put on Delhi, referring to it on Monday as Russia's “largest or second largest oil buyer”.

Trump, who has previously denounced India as a “tariff king”, blamed New Delhi’s purchases of Russian weapons and oil for the additional rate, which puts at risk India’s largest export market, worth $87bn in the year to the end of March.